Network management system, network, method and computer program product

ABSTRACT

Known network management systems for managing traffic signals in a network store node/link parameter signals and traffic parameter signals and calculate solutions defining intermediate nodes/links situated between sources and destinations for transporting said traffic signals from said sources to said destinations via said intermediate nodes/links and calculate route information per solution. By storing node/link parameter signals and traffic parameter signals for several situations (like several predictions in the future) and calculating solutions for each situation and then selecting a solution per situation, the network management system will manage the network more advantageously, especially when solutions are compared with each other, and when a solution is selected per situation in dependence of comparison results (comprising similarities/differences between solutions of different situations). Said route information may comprise link load parameters and/or resource consumption parameters and/or fairness parameters and/or throughput parameters.

The invention relates to a network management system for managingtraffic signals in a network comprising nodes/links, which networkmanagement system comprises a memory for storing node/link parametersignals defining nodes/links and for storing traffic parameter signalsdefining said traffic signals to be transported via nodes/links andcomprising a calculator coupled to said memory for calculating solutionsdefining intermediate nodes/links situated between sources anddestinations for transporting said traffic signals from said sources tosaid destinations via said intermediate nodes/links and for calculatingroute information per solution.

The functionality of such a network management system is known from thearticle “Multi-objective Traffic Engineering of IP Networks Using

Label-Switched Paths”, Networks 2000 conference, Toronto, Canada, Sep.10-15, 2000, which discloses a traffic engineering algorithm also usablefor short term capacity planning. Said algorithm solves a trafficengineering problem formulated as a mixed integer linear programcomprising at least one objective and several constraints by calculatingsolutions defining intermediate nodes/links situated between sources anddestinations for transporting said traffic signals from said sources tosaid destinations via said intermediate nodes/links and by calculatingroute information per solution.

The known network management system is disadvantageous, inter alia, dueto solving each traffic engineering problem solely per problem.

It is an object of the invention, inter alia, of providing a networkmanagement system as defined in the preamble which can handle a group ofinteracting traffic engineering problems.

The network management system according to the invention ischaracterised in that said network management system comprises aselector, with said memory comprising node/link parameter signals andtraffic parameter signals for several situations and with saidcalculator calculating solutions for each situation, and with saidselector selecting a solution per situation.

By providing the network management system with said selector, asolution per situation can be calculated, with each situationcorresponding with at least one traffic engineering problem.

The invention is based on the insight, inter alia, that trafficengineering problems occur all the time, with one traffic engineeringproblem often not being completely independent from neighbouringproblems.

The invention solves the problem, inter alia, of providing a networkmanagement system which can handle a group of interacting trafficengineering problems.

At least a part of the inventivity of the invention is situated, interalia, in realizing that traffic engineering problems (and theirsolutions) sometimes interact and therefore usually cannot be regardedto be completely independent from one another.

A first embodiment of the network management system according to theinvention is characterised in that said network management systemcomprises a comparator coupled to said calculator for comparingsolutions with each other.

By introducing said comparator, for example several solutions allbelonging to the same situation and therefore all solving the sameproblem in different ways can be compared with each other.

A second embodiment of the network management system according to theinvention is characterised in that said selector is coupled to saidcomparator for selecting a solution per situation in dependence of atleast one comparison result.

By coupling said selector to said comparator, selections can now be madedependently from comparison results.

A third embodiment of the network management system according to theinvention is characterised in that at least one comparison resultcomprises similarities/differences between solutions of differentsituations.

In case at least one comparison result comprisessimilarities/differences between solutions of different situations, saidcomparator can now compare several solutions belonging to differentsituations, thereby taking into account the fact that different trafficengineering problems (and their solutions) interact with each other.

A fourth embodiment of the network management system according to theinvention is characterised in that said network management systemcomprises a processor which comprises said calculator and/or saidselector and/or said comparator.

By introducing said processor, for example having a calculating functionand/or a selecting function and/or a comparing function, said calculatorand/or said selector and/or said comparator are implementedadvantageously.

A fifth embodiment of the network management system according to theinvention is characterised in that said route information comprises linkload parameters and/or resource consumption parameters and/or fairnessparameters and/or throughput parameters.

Said link load parameters and/or resource consumption parameters and/orfairness parameters and/or throughput parameters are just non-limitativeexamples of said route information for supporting said selecting.

A sixth embodiment of the network management system according to theinvention is characterised in that each situation corresponds with aprediction in the future.

With each situation corresponding with a prediction in the future,traffic is forecasted for moments in time lying in the future and yet tocome, with the corresponding traffic engineering problems being solvedadvantageously due to taking into account any interactions between theseproblems (and their solutions).

The invention further relates to a network comprising nodes/links and atleast one network management system for managing traffic signals in saidnetwork, which network management system comprises a memory for storingnode/link parameter signals defining nodes/links and for storing trafficparameter signals defining said traffic signals to be transported vianodes/links and comprising a calculator coupled to said memory forcalculating solutions defining intermediate nodes/linkes situatedbetween sources and destinations for transporting said traffic signalsfrom said sources to said destinations via said intermediate nodes/linksand for calculating route information per solution.

The network according to the invention is characterised in that saidnetwork management system comprises a selector, with said memorycomprising node/link parameter signals and traffic parameter signals forseveral situations and with said calculator calculating solutions foreach situation, and with said selector selecting a solution persituation.

Embodiments of the network according to the invention are incorrespondence with embodiments of the network management systemaccording to the invention.

The invention yet further relates to a method for managing trafficsignals in a network comprising nodes/links, which method comprises afirst step of calculating solutions defining intermediate nodes/linkssituated between sources and destinations for transporting said trafficsignals from said sources to said destinations via said intermediatenodes/links and comprises a second step of calculating route informationper solution, with node/link parameter signals defining nodes/links andtraffic parameter signals defining said traffic signals to betransported via nodes/links being stored in a memory.

The method according to the invention is characterised in that saidmethod comprises a third step of selecting a solution per situation,with said memory comprising node/link parameter signals and trafficparameter signals for several situations, and with solutions beingcalculated for each situation.

Embodiments of the method according to the invention are incorrespondence with embodiments of the network management systemaccording to the invention.

The invention also relates to a computer program product for managingtraffic signals in a network comprising nodes/links, which computerprogram product is to be run via processor coupled to a memory forstoring node/link parameter signals defining nodes/links and for storingtraffic parameter signals defining said traffic signals to betransported via nodes/links, which computer program product comprises afirst function of calculating solutions defining intermediatenodes/links situated between sources and destinations for transportingsaid traffic signals from said sources to said destinations via saidintermediate nodes/links and comprises a second function of calculatingroute information per solution.

The computer program product according to the invention is characterisedin that said computer program product comprises a third function ofselecting a solution per situation, with said memory comprisingnode/link parameter signals and traffic parameter signals for severalsituations, and with solutions being calculated for each situation.

Embodiments of the computer program product according to the inventionare in correspondence with embodiments of the network management systemaccording to the invention.

The article “Multi-objective Traffic Engineering of IP Networks UsingLabel-Switched Paths”, Networks 2000 conference, Toronto, Canada, Sep.10-15, 2000, discloses a traffic engineering algorithm also usable forshort term capacity planning. Said algorithm solves a trafficengineering problem formulated as a mixed integer linear programcomprising at least one objective and several constraints. The article“Choosing the Objectives for Traffic Engineering in IP Backbone Networksbased on Quality-of-Service Requirements”, QoFIS 2000 conference,Berlin, Germany, September, 2000, also discloses a traffic engineeringalgorithm solving a traffic engineering problem formulated as a mixedinteger linear program comprising at least one objective and severalconstraints. Both articles are considered to be incorporated byreference.

The invention will be further explained more detailledly at the hand ofan example shown in the drawings, whereby

FIG. 1 discloses a network management system according to the inventioncomprising a memory, a calculator, a selector and a comparator, and

FIG. 2 discloses a network comprising nodes/links with node/linkparameter signals traffic parameter signals being defined for threesituations shown horizontally next to each other, with three solutionsbeing shown vertically per situation, and

FIG. 3 discloses a flow chart illustrating a method according to theinvention and a computer program product according to the invention.

FIG. 1 discloses a network management system 100 according to theinvention comprising a memory 101 coupled via a connection 120 to aprocessor system 102 which is coupled via a connection 121 to a switch103 which is to be coupled via connections 123 to nodes. Processorsystem 102 comprises a first interface 111 coupled to connection 120 andto a bus 122 and comprises a second interface 112 coupled to connection121 and to bus 122. Bus 122 is further coupled to a calculator 110, to aselector 113 and to a comparator 114.

Memory 101 comprises three fields, each field corresponding with asituation, the first situation defining traffic signals to betransported from a node A to a node G with a capacity of 10 Mbyte andtraffic signals to be transported from a node B to node G with acapacity of 5 Mbyte both at a future time t1. The second situationdefines traffic signals to be transported from node A to node G with acapacity of 4 Mbyte and traffic signals to be transported from node B tonode G with a capacity of 9 Mbyte both at a future time t2. The thirdsituation defines traffic signals to be transported from node A to nodeG with a capacity of 8 Mbyte and traffic signals to be transported fromnode B to node G with a capacity of 6 Mbyte both at a future time t3.Further, but not shown, memory 101 comprises topology informationdefining the topology of a network shown in FIG. 2. This topologyinformation is stored in the form of node/link parameter signalsdefining nodes/links. Said traffic signals to be transported are storedin the form of traffic parameter signals defining said traffic signalsto be transported via said nodes/links.

FIG. 2 discloses a network comprising a node A and a node B each one ofthem being coupled to a node C which is further coupled via a node D toa node G and via a node E and a node F to said node G. FIG. 2 furtherdiscloses said three situations at future times t1, t2 and t3, anddiscloses a matrix of nine blocks, a first row comprising firstsolutions for said three situations, a second row comprising secondsolutions for said three situations and a third row comprising thirdsolutions for said three situations.

Said first row comprising first solutions for said three situations isthe result of so-called shortest path calculations, which have been madein accordance with, inter alia, the referenced prior art documents, withsaid first solutions defining intermediate nodes/links (for allsituations nodes C and D) situated between sources (for all situationsnode A and node B respectively) and destinations (for all situationsnode G) for transporting said traffic signals (first situation: 10 Mbyteand 5 Mbyte respectively; second situation: 4 Mbyte and 9 Mbyterespectively; third situation: 8 Mbyte and 6 Mbyte respectively) fromsaid sources to said destinations via said intermediate nodes/links andfor calculating route information (maximum link load M and resourceconsumption R) per solution (first situation: M=10+5=15 Mbyte,R=10+10+10+5+5+5=45 Mbyte; second situation: M=4+9=13 Mbyte,R=4+4+4+9+9+9=39 Mbyte; third situation: M=8+6=14 Mbyte,R=8+8+8+6+6+6=42 Mbyte).

Said second row comprising second solutions for said three situations isthe result of further path calculations, which have been made inaccordance with, inter alia, the referenced prior art documents, withsaid second solutions defining intermediate nodes/links (firstsituation: nodes C and E and F and nodes C and D respectively; secondsituation: nodes C and D and nodes C and E and F respectively; thirdsituation: nodes C and E and F and nodes C and D respectively) situatedbetween sources (for all situations node A and node B respectively) anddestinations (for all situations node G) for transporting said trafficsignals (first situation: 10 Mbyte and 5 Mbyte respectively; secondsituation: 4 Mbyte and 9 Mbyte respectively; third situation: 8 Mbyteand 6 Mbyte respectively) from said sources to said destinations viasaid intermediate nodes/links and for calculating route information(maximum link load M and resource consumption R) per solution (firstsituation: M=10 Mbyte, R=10+10+10+10+5+5+5=55 Mbyte; second situation:M=9 Mbyte, R=4+4+4+9+9+9+9=48 Mbyte; third situation: M=8 Mbyte,R=8+8+8+8+6+6+6=50 Mbyte).

Said third row comprising third solutions for said three situations isthe result of yet further path calculations, which have been made inaccordance with, inter alia, the referenced prior art documents, withsaid third solutions defining intermediate nodes/links (first situation:nodes C and D and nodes C and E and F respectively; second situation:nodes C and E and F and nodes C and D respectively; third situation:nodes C and D and nodes C and E and F respectively) situated betweensources (for all situations node A and node B respectively) anddestinations (for all situations node G) for transporting said trafficsignals (first situation: 10 Mbyte and 5 Mbyte respectively; secondsituation: 4 Mbyte and 9 Mbyte respectively; third situation: 8 Mbyteand 6 Mbyte respectively) from said sources to said destinations viasaid intermediate nodes/links and for calculating route information(maximum link load M and resource consumption R) per solution (firstsituation: M=10 Mbyte, R=10+10+10+5+5+5+5=50 Mbyte; second situation:M=9 Mbyte, R=4+4+4+4+9+9+9=43 Mbyte; third situation: M=8 Mbyte,R=8+8+8+6+6+6+6=48 Mbyte).

According to prior art, network management system 100 either comprisesmemory 101 and calculator 110 and is located in each node, or comprisesmemory 101 and calculator 110 and switch 103 which is coupled to (atleast some of) the nodes. Memory 101 then just comprises one fieldcorresponding with one situation, and memory 101 comprises topologyinformation defining (at least a part of) the topology of the networkshown in FIG. 2. Calculator 110 calculates one or more solutions forsaid one situation, dependent upon the available time. In case of onesolution being calculated, this one solution is the only one andtherefore chosen to be the one for solving the problem. In case of morethan one solution being calculated, the last one usually is the bestsolution and therefore chosen to be the one for solving the problem(whereby it should be noted that previous and therefore usually worsesolutions are not kept/stored due to being not that good as the lastone). After this, a next situation can be handled, etc. Or, memory 101may comprise more than one field, each one corresponding with adifferent situation, but even then each situation is taken care ofindependently from the others.

According to the invention, the network management system furthercomprises at least said selector 113 and possibly further comprises atleast said comparator 114, and at least several solutions per situationare calculated by calculator 110 and kept/stored this time, for allowinga selection.

According to a first possibility, route information parameters (like forexample the maximum link load M and/or the resource consumption R)calculated per solution per situation are used to let calculator 110calculate thresholds for said route information parameters (for exampleby performing a function on the route information parameters calculatedfor all solutions in one situation or calculated for specific solutionsfor specific situations), after which said selector 113 selects asolution per situation for example in dependence of the thresholds beingexceeded or not by the route information parameters of that solutionand/or in dependence of the route information parameters of thatsolution lying closest to said thresholds etc.

According to a second possibility, possibly in addition to the firstpossibility, said comparator 114 compares solutions of one situationwith each other for supporting said selection for selecting a solutionper situation in dependence of at least one comparison result.

According to a third possibility, possibly in addition to the firstand/or second possibility, said comparator 114 compares solutions ofdifferent situations with each other, as a result of which at least onecomparison result will comprise similarities/differences betweensolutions of different situations. For example, as shown in FIG. 2,between any pair of solutions belonging to neighbouring situations, thecalculated paths per traffic signal are compared, resulting in a numberof path amendments per said pair of solutions. As can be derived fromFIG. 2, a transition from the second solution of the first situation tothe second solution of the second situation requires two pathamendments, a transition from the second solution of the secondsituation to the second solution of the third situation requires twopath amendments, a transition from the third solution of the firstsituation to the third solution of the second situation requires twopath amendments, and a transition from the third solution of the secondsituation to the third solution of the third situation requires two pathamendments. But a transition from the third solution of the firstsituation to the second solution of the second situation requires no(zero) path amendments, and a transition from the second solution of thesecond situation to the third solution of the third situation alsorequires no (zero) path amendments. Then, for example in case of anumber of path amendments being required to be as little as possible,said selector 113 will select the third solution of the first situation,the second solution of the second situation and the third solution ofthe third situation.

According to a fourth possibility, possibly in addition to the firstand/or second and/or third possibility, said comparator 114 comparessolutions of different situations with each other, as a result of whichat least one comparison result will comprise similarities/differencesbetween solutions of different situations. Then calculator 110 willcalculate thresholds for said route information parameters and/or forsaid similarities/differences (for example by performing a function onthe route information parameters calculated for all solutions in onesituation or calculated for specific solutions for specific situationsand/or for example by performing a function on saidsimilarities/differences), after which said selector 113 selects asolution per situation, for example in dependence of the thresholdsbeing exceeded or not by the route information parameters of thatsolution and/or by the similarities/differences of that solution, and/orin dependence of the route information parameters of that solutionand/or similarities/differences of that solution lying closest to saidthresholds, and/or by for example firstly minimizing the maximum linkload M and/or secondly minimizing the resource consumption R etc.

Each part of network management system 100, shown in the form of a blockor not shown, can be 100% hardware, 100% software or a mixture of both.Therefore, a calculator also comprises a calculating function, aselector also comprises a selecting function, and a comparator alscomprises a comparing function. Each block shown or not shown can beintegrated with each other block shown and/or not shown. In addition tothe memory 101 shown, each block can have a further memory not shown forefficiency purposes. One or more of said calculator 110, first interface111, second interface 112, selector 113 and comparator 114 may be(partly or entirely) integrated into processor system 102.

The bus 122 may be replaced by separate connections, thereby for exampleintroducing multiplexers and demultiplexers in. Memory 101 can be forexample a DPRAM, or a server controlled processor system 102 or by afurther processor not shown, or a combination of a memory and(de)multiplexer, etc. Selector 113 can be for example an addressgenerator for addressing said memory 101 for making a selection.Comparator 114 may receive parameters from memory 101 and/or fromprocessor system 102 and/or from a further processor not shown, and mayreceive comparison values from processor system 102 and/or from afurther processor not shown. First interface 111 and second interface112 and switch 103 for example comprise shift registers and/or buffersand/or further processors/memories, etc.

The term ‘node(s)/link(s)’ correspond with the term ‘node(s) and/orlink(s)’. Instead of each situation corresponding with a prediction inthe future, whereby traffic is forecasted for moments in time lying inthe future and yet to come, other choices could be made, like eachsituation corresponding with a different amount of traffic to beexpected. Then, dependently upon the amount of traffic to be routedthrough the network, for example the next hour or the next day, asolution for the corresponding situation is to be selected. But whatevera situation is corresponding with, the corresponding traffic engineeringproblems are solved advantageously due to taking into account anyinteractions between these problems (and their solutions). Said routeinformation (parameters) may comprise link load parameters and/orresource consumption parameters and/or fairness parameters and/orthroughput parameters, but this is just a non-limitative list of saidroute information (parameters) for supporting said selecting.

In the flow chart shown in FIG. 3 the blocks have the following meaning:

-   Block 300: calculate (for example by performing shortest path    calculations and further path calculations and yet further path    calculations) solutions per situation for all situations and    calculate route information parameters per calculated solution and    calculate thresholds and store all calculated solutions and all    calculated route information parameters and all calculated    thresholds; goto 301.-   Block 301: select a first starting point in the previously stored    calculated solutions; goto 302.-   Block 302: calculate (for example by again performing shortest path    calculations, but now by starting from said starting point and using    a cost parameter corresponding with the number of amendments between    said stored (subsequent) solutions to be minimized) new solutions    and store them; goto 303.-   Block 303: is said starting point the last possible starting point    in the stored calculated solutions? If yes, goto 305, if no, goto    304.-   Block 304: select a next starting point in the previously stored    calculated solutions; goto 302.-   Block 305: select the best new solutions; in case of more than one    option, take into account thresholds etc.

The method according to the invention and the computer program productaccording to the invention function as follows. Calculate (for exampleby performing shortest path calculations and further path calculationsand yet further path calculations) solutions per situation for allsituations and calculate route information parameters per calculatedsolution and calculate thresholds and store all calculated solutions andall calculated route information parameters and all calculatedthresholds (Block 300; goto 301). Select a first starting point in thepreviously stored calculated solutions (Block 301; goto 302). Calculate(for example by again performing shortest path calculations, but now bystarting from said starting point and using a cost parametercorresponding with the number of amendments between said stored(subsequent) solutions to be minimized) new solutions and store them(Block 302; goto 303). Is said starting point the last possible startingpoint in the stored calculated solutions (Block 303)? If no, select anext starting point in the previously stored calculated solutions (Block304; goto 302). If yes, select the best new solutions (Block 305).Usually said calculated new solutions will not offer more than oneoption. But in case of more than one option, take into accountthresholds etc. and/or for example firstly minimize the maximum linkload M and/or secondly minimize the resource consumption R. Of course,this could also be implemented when calculating said new solutions (inBlock 302).

For implementing this method according to the invention and/or thiscomputer program product according to the invention, any programminglanguage can be used. Of course, the flow chart in FIG. 3 is just anexample. Many alternatives are possible without departing from the scopeof this invention. In practice, for example, said shortest pathcalculations (and further path calculations and yet further pathcalculations) on the one hand and said shortest path calculations nowstarting from said starting point and using a cost parametercorresponding with the number of amendments between said stored(subsequent) solutions to be minimized on the other hand could becombined into a combined shortest path calculation by adding one or morefictive nodes and defining certain (different) cost parameters forcertain (fictive) links.

1-10. (canceled)
 11. A network management system for managing trafficsignals in a network comprising nodes/links, comprising: a calculatorfor calculating solutions defining intermediate nodes/links fortransporting traffic signals from a source to a destination for each ofa plurality of situations; a comparator for comparing solutions of asame situation with each other and for comparing solutions of differentsituations with each other; and a selector for selecting a solution foreach of the plurality of situations based on at least one comparisonresult of the comparing solutions of the same situation and at least onecomparison result of the comparing solutions of different situations.12. The network management system of claim 11, wherein the calculator isfurther for calculating route information parameters comprising at leastone of a maximum link load and a resource consumption.
 13. The networkmanagement system of claim 12, wherein the selector is further forselecting the solution for each of the plurality of situations byminimizing the maximum link load.
 14. The network management system ofclaim 12, wherein the selector is further for selecting the solution foreach of the plurality of situations by minimizing the resourceconsumption.
 15. The network management system of claim 12, wherein theselector is further for selecting the solution for each of the pluralityof situations based on a comparison of one or more of the routeinformation parameters to a threshold.
 16. The network management systemof claim 11, wherein each of the plurality of situations defines trafficsignals to be transported from the source to the destination.
 17. Thenetwork management system of claim 11, wherein each of the plurality ofsituations defines a capacity of the traffic signals.
 18. The networkmanagement system of claim 11, wherein the solutions comprise a shortestpath calculation.
 19. The network management system of claim 11, whereinthe plurality of situations corresponds to predictions of trafficforecasts at different points in time in the future.
 20. The networkmanagement system of claim 11, wherein the plurality of situationscorresponds to different amounts of traffic.
 21. A network comprisingnodes/links and at least one network management system for managingtraffic signals in said network, said network management systemcomprising: a calculator for calculating solutions defining intermediatenodes/links for transporting traffic signals from a source to adestination for each of a plurality of situations; a comparator forcomparing solutions of a same situation with each other and forcomparing solutions of different situations with each other; and aselector for selecting a solution for each of the plurality ofsituations based on at least one comparison result of the comparingsolutions of the same situation and at least one comparison result ofthe comparing solutions of different situations.
 22. The network ofclaim 21, wherein the calculator is further for calculating routeinformation parameters comprising at least one of a maximum link loadand a resource consumption.
 23. The network of claim 21, wherein theselector is further for selecting the solution for each of the pluralityof situations by minimizing the maximum link load.
 24. The network ofclaim 21, wherein the selector is further for selecting the solution foreach of the plurality of situations by minimizing the resourceconsumption.
 25. The network of claim 21, wherein the selector isfurther for selecting the solution for each of the plurality ofsituations based on a comparison of one or more of the route informationparameters to a threshold.
 26. A method for managing traffic signals ina network comprising nodes/links, comprising: calculating solutionsdefining intermediate nodes/links for transporting traffic signals froma source to a destination for each of a plurality of situations;comparing solutions of a same situation with each other and comparingsolutions of different situations with each other; and selecting asolution for each of the plurality of situations based on at least onecomparison result of the comparing solutions of the same situation andat least one comparison result of the comparing solutions of differentsituations.
 27. The method of claim 26, wherein each of the plurality ofsituations defines traffic signals to be transported from the source tothe destination.
 28. The method of claim 26, wherein each of theplurality of situations defines a capacity of the traffic signals.
 29. Acomputer readable medium storing computer program instructions formanaging traffic signals in a network comprising nodes/links, which,when executed by a processor, cause the processor to perform operationscomprising: calculating solutions defining intermediate nodes/links fortransporting traffic signals from a source to a destination for each ofa plurality of situations; comparing solutions of a same situation witheach other and comparing solutions of different situations with eachother; and selecting a solution for each of the plurality of situationsbased on at least one comparison result of the comparing solutions ofthe same situation and at least one comparison result of the comparingsolutions of different situations.
 30. The computer readable medium ofclaim 29, wherein the solutions comprise a shortest path calculation.